So it sounds like you are not using FusionAuth's hosted login pages, but are building your own integration with Facebook. And then you are calling https://fusionauth.io/docs/v1/tech/apis/identity-providers/facebook#complete-the-facebook-login

Is that correct?

If so, I think you'd need to make the additional calls to Facebook to get the name and picture and then to update the FusionAuth user profile.

When you use the hosted login pages, we handle that for you, but when you build your own integration, all we do is log the user in (and possible create them and register them for your application, if configured to do so).